#include <stdio.h>  
  
int sum(int n, int m) {  
    if (m == n)  
        return n;  
    return sum(n, m - 1) + m;  
}  
  
int main() {  
    int n, m;  
    if (scanf("%d%d", &n, &m));  
    int ans = sum(n, m);  
    printf("The sum from %d to %d is %d.\n", n, m, ans);  
    return 0;  
}  